Electronic guitar



Nov. 9, 1965 R, H, MURRELL 3,217,079

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Unitedv States Patent .O

3,217,079 ELECTRONIC GUITAR Robert H. Murrell, 507 Amicable Bldg., Waco, Tex. Filed June 25, 1962, Ser. No. 204,827 13 Claims. (Cl. 84-1.16)

This invention relates to a guitar and an associated electronic circuit by which the guitar may simulate an organ.

An object of the present invention is to provide a guitar and an associated electronic circuit by which a guitarist, by normal playing action, can simulate an organ including all stops, and effects, such as chimes, harp, celeste, percussion, etc.

Another object of the present invention is to provide a guitar and an associated electronic circuit including organ tone generators in which the guitar may be played and the organ eifect produced either selectively or simultaneously.

An additional object of the present invention is to provide a guitar and an associated electronic circuit for simulating an organ, wherein the strings and frets on the guitar function as switches for keying the electronic circuit.

A further object of the present invention is to provide a guitar and an associated electronic circuit for simulating an organ wherein the circuit components are of such nature that they may be built into the latter with a minimum modication of existing guitars.

Still another object of the present invention is to provide a guitar and an associated electronic circuit for simulating an organ which will play any combination of notes on any selected string.

Additional objects, advantages and improvements will become apparent from the following specication, taken in connection with the accompanying drawings, in which:

FIGURE 1 is a top plan view of a section of the neck or finger board of a guitar, modified according to the present invention;

FIGURE 2 is a sectional view, taken on the section line 2 2 of FIGURE 1 and looking in the direction of the arrows, showing the electrical connections to the frets;

FIGURE 3 is a side elevational view of the iinger board shown in FIGURE 1, showing the electrical connections to the frets;

FIGURE 4 is a circuit diagram showing the electronic keying circuit;

FIGURE 5 is a circuit diagram showing the electromechanical keying arrangement;

FIGURE 6 is a main circuit diagram showing an alternative arrangement in which standard frets on the guitar are employed and relays are used for keying instead of vacuum tubes; and,

FIGURE 7 is an auxiliary circuit diagram showing the key board arrangement and the individual power supplies, as used in the main circuit according to FIGURE 6.

Referring now to the drawings in detail and to FIG- URES 1 and 2 in particular, there is here shown at 10 the neck or finger board of a guitar. This finger board is secured at one end to a body or sound chamber (not shown) of the guitar. A plurality of strings 11, six (6) being the conventional number, extend along the linger board 10 in taut relationship. In the conventional manner of playing a guitar these strings are picked or plucked. The strings are made of high quality steel, which of course is la fair electrical conductor. At their rear ends the strings 11 are supported on a bridge (not shown) and .are secured to a tail piece (also not shown) on the sound chamber. This tail piece functions as a ground according to the present invention. The ground is shownv as G-l in FIGURE 3 f C 3,217,079 ce Patented'Nov. 9, 1965 and one of the strings 11 is connected by a conductor 12 to same. Also, at their forward ends the strings 11 are secured to tensioning shafts (not shown), which are rotatably mounted adjacent the outer end of the finger board. Along the linger board 10 the strings 11 are positioned above a series of frets 13. As is well known, in playing the instrument a right-handed player holds the latter by grasping the iinger board 10 in his left hand and plays same by plucking the strings 11 with his right hand. By pressing one of the strings down with a finger of his left hand, he may vary the eiiective length of the latter and hence the period of vibration and the tone developed in the tone chamber (not shown).

AccordingY to the present invention, the frets 13 are divided lengthwise into segments, one for each string 11, which, as shown, are six (6) in number. Since the nger board 10 is conventionally made of plastic or wood, both of which are insulating materials, each string 11 and any segment of a fret 13 beneath same functions asa circuit making and breaking device, or a switch, in the present invention. Along the under side of the finger board 10 there are formed a pair of lengthwise extending grooves 15-15, each having its axis displaced approximately 30 from the top plane of the finger board. Holes 14 are drilled in the finger board 10` from positions adjacent the fret segments 13 and these holes intersect the grooves 15-15; the holes 14 from the fret segments on one side of the longitudinal center line of the iinger board intersect one of the grooves 15 and the holes from the fret segments on the other side of the longitudinal center line intersect the other groove. Conductors 16 are connected to the fret segments 13 and extend through the holes 14 and the longitudinal grooves 15 to octave selector switches SW-2, to be later described, and which are mounted on the sound chamber (not shown). The contacts of the octave selector switches are connected by conducto-.rs 17, 18 and '19 to a terminal plug (not shown), wich is also mounted on the sound chamber.

In the keying circuit according to FIGURE 4, there is one stage for each string on the guitar but only two stages are shown. The first stage includes a tone generator CT, which is connected by a conductor 22 through two blocking capacitors C1 and C2 in series to the grid of an electron tube V1; similarly the second stage includes a tone generator BT, which is connected by a conductor 24 through two blocking capacitors C1 and C2 in series to the grid of an electron tube V2. The tone generators CT, BT, etc. may be any standard organ tone generators, although the Hammond is not well suited for the present purpose.

The complete circuit for producing one tone is illustrated and described. Additional conductors 17 and 19 extend from the tone generators CT and BT to similar circuits (not shown) for producing other tones.

The circuit making and breaking devices comprised by the strings 11 and fret segments 13 on FIGURES l and 2 are here designated SW-l. The conductors 16 from the switches SW-l are connected to the movable contact members of octave selector switches `SW2. These switches are each single pole, triple position multiple gang switches with a pole for each note to be controlled. In the present arrangement there could be a total of forty-one of these switches. The gang switches comprised by the switches SW-2 of each stage are mounted on the body or sound chamber (not shown) of the guitar. The movable contact members of the switches SW-2 are interconnected by a mechanical link 25 for conjoint operation. The switches SW-Z are used as a register selector and allow the player to extend the tone range up or down one octave for more varied eifects.

In the conventional pipe organ the tones developed are a function of the physical lengths of the pipes. The usual present day pipe organ has what is called 4 ft., 8 ft. and 16 ft. stops. In reality these are only octave relationships, with the tones developed by the 8 ft. pipes being one octave higher than those developed by the 16 ft. pipes, and the tones developed by the 4 ft. pipes being one octave higher than those developed by the 8 ft. pipes. Now with the instrument according to the present invention, one may be playing with the 8 ft. stops set and wish to switch to the 16 ft. stops. Through the octave selector switches SW-Z, these, as stated, being mounted on the body of the guitar, this change may be made with a minimum of effort.

The grids of the electron tubes are connected to a source of negative biasing potential through a conductor 21 and a pair of balancing resistors R1 and R2 in series. The center contact of each switch SW-Z is connected by a conductor 18, through a resistor R3 to the midpoint of the resistors R1 and Rz. A conductor 20 connects this mid-point to ground through a capacitor C3. The R-C circuit comprised by the resistor R3 and the capacitor C3 provides a time delay for the output of the tone generator CT, or BT, to the electron tube V1, or V2, respectively, and also functions as a click suppressor.

The Icathodes of the electron tubes V1 and V2 are connected to ground at G3 by conductors 26. Positive potential is supplied to the anodes of the tubes V1 and V2 through anode resistors R4 and conductors 27. The anodes are also connected by conductors 28 and through load resistors R to a conductor 29 and a capacitor C1 in the tone coloring circuit.

When a string 11 is pressed against a fret segment 13 to play one note it will also contact an adjacent fret segment to play another note. This is shown in FIGURE 3 where the string 11 is depressed by the nger to contact a fret segment f13 and play a C note but also contacts an adjacent fret segment 13 and would signal a B note. The keying circuit of FIGURE 4 prevents the reception of these interfering signals.V A conductor 23 is connected between the blocking capacitors C1 and C2` of one stage and the output side of the switch SW-l of the next higher stage.

In the electro-mechanical system according to FIGURE 5, the contacts of relays are used instead of vacuum tubes to do the keying, Two stages including relays Ry, and Ry-2 are here shown and the relay Ry-S for another stage. One selector switch SW-2 is shown with its outer contacts connected by conductors 17 and 19 to` the windings of additional relays Ry--Ry for keying two other tones. It will 'be understood that the two other selector switches SW-Z each similarly have their outside contacts connected in like manner by a pair of conductors to the windings of two relays (not shown) for keying additional tones. The switches SVV-1 are here also circuit making and breaking devices comprised by the strings 11 and fret segments 13 on the guitar. These switches are connected to ground at G-l on one side; on the other side they are connected by conductors 17 and 1,9, respectively, to the windings of relays Ry, which operate the octave selector. From the central contacts of the switches SW-Z conductors 30 extend to the windings of the relays Ry-l, Ry-2, and Ry-3, respectively. Each of these latter relays has five pairs of contacts.

The other sides of the windings of the relays Ry'1, Ry-Z and Ry-3 are connected by conductors 31 to the movable .contact of the fifth pair of contacts; the corresponding fixed contact 9 is connected by a conductor 32 to a l2-volt source of electro-motive force. The fixed contact 8 of the fourth set of ycontacts is connected by a conductor 33 to a switch SW-S, which is the percussion tab; the other side of the switch SW-Sv is connected by a conductor 34 to a 30G-volt source of electromotive force; the movable contact 7 of the fourth set is connected by a conductor 35 to the percussion connection of the corresponding tone generator. The fixed contact 6 of the third set of contacts is connected by one of the conductors 28 to the tone coloring circuit, as in the previous modification; the movable Contact 5 of this set is connected by a conductor 36 to one output terminal of the corresponding tone generator. The movable contact 5 closes on the xed contact 4 of the second set; when the relay is in normal position, and on the contact 6 of the third set, when the relay is operated. The fixed contact 4 of the second set is connected by a conductor 37 to the fixed contact 1 of the first set. A ground at G-4 is placed on the contacts 1 and 4 through a conductor 38. The movable contact 2 of the first set closes on the fixed contact 1, when the relay is in normal position. This movable contact 2 is connected by a con ductor 39 to the other output terminal of the corresponding tone generator. The movable contact 2 also closes on a fixed contact 3, when the relay is operated. This contact 3 is connected by the other conductor 28 to the tone coloring circuit.

The tone generators used in FIGURE 5 are conventional. Each tone generator has three different octave scale outputs shown as leads 35, 36 and 39, respectively. The output 36 may represent the normal playing octave scale of the tone generator while the output 39 represents the next higher scale and output 35 may represent the next lower scale range below the scale of output 36 which may also be a sustaining scale, generally connoted in the art as a percussion scale.

In operation, it is noted that many organs bring the tones directly to the key contacts. In the unkeyed posii tion, that is with no keys pressed down, all of the tones are grounded. This is the situation in the circuit arrange-f ment represented here. Let it again Ibe assumed that a C2 note is to be played. The sequence of operations will be` as follows: By pressing a string 11 against the selected fret segment 13, a ground is placed on the winding of the relay Ry-Z at one end of the latter. Voltage is then applied through the normally closed contacts 9-10 of the relay Ry-S in the next stage to the winding of the relay Ry-Z at the other end of the latter. The latter relay is operated moving its contacts to close circuits in the following manner: the grounds are removed from the tone generator output 36-39, allowing the tones to pass through the contacts 3 and 6 and over the conductors 28-28 to the tone coloring circuit. If the percussion or sustaining switch SW-4 is closed, a voltage of 300 volts is applied through the contacts 7 and 8 to the tone generator.

As in the preceding modification, whenever a string 11 is depressed, it simultaneously contacts two fret segments 13 on the opposite sides of the point of depression. It is necessary to mute the lower note produced by the string contacting the fret segment on one Vside of the point of depression. This is accomplished in the present circuit by the winding of each relay coil Ry-l, Ry-Z, Ry-3, etc. being connected through the winding contacts of the relay in the stage one-half tone higher. Thus, when the relay Ry-Z is operated, the contacts 9-10 of the relay Ry-3 in the next adjacent stage are open and it will be impossible to play the adjacent B note.

The function of the octave selector switch SW-Z is the same as in the preceding modification. In its middle position, as shown, the proper tones are keyed. By turning the switch SW-Z clockwise, as shown in FIGURE 5, tones one octave higher will be keyed; likewise, by turning same counterclockwise, tones one octave lower will be keyed.

I The circuit arrangement herein described is highly practrcal due to being completely universal. Any number of contacts can be used and they close the circuits in the same manner as in an organ. Some organs have only two contacts while one, the Hammond, has nine. However, by proper selection of the relays, the invention can be adapted to any existing organ.

In the circuit arrangement shown in FIGURES 6 and 7 the front segments 13 are not divided. This minimizes the,

modification required' in apply-ing the intenties te existing guitars. The strings 11 however are electrically insulated from each other. Six twenty-four-volt power supplies are used, one for each string 11` Also, a separate relay Ry-l, Ry-Z, Ry-3 etc. is used for each fret 13. One output terminal of each power supply 40 is connected by a conductor r41 to one side of the winding of each relay Ry-l, Ry-2, Ry-3, etc. at the frets along the corresponding string 11. The conductors 41 are interconnected by a conductor 42, which is a common return lto the power supply. The other output terminal of each power supply is connected by a conductor 43 to the movable contact members of the switches SW-1. As shown in the circuit diagram of FIGURE 7, the movable contact member of the switch SW-l at each fret 13 along a string 11 is connected by a conductor 44 to the movable contact member of the switch SW-l at the next adjacent fret. It will be undersood however that this connection is actually through the string 11, as shown in FIGURE 6.

One side of the winding of each relay Ry-1, Ry-Z, Ry-3, etc is connected by a conductor 16 to the xed contact of the switches SW-l by a conductor 16, as in the previous modifications; the other side of the winding of each relay is connected by a conductor 45 to a contact 4 of a normally closed third pair of contacts 4-5 on the relay in the next adjacent stage. This pair of contacts performs the same function as the normally closed pair of contacts 9-10 on the relays Ryel, Ry-Z, Ry-3 etc. in the preceding modiiication. The contact 5 of the pair of contacts `45 is connected to the conductor 41 and the corresponding 24 volt power supply, this connection not being shown on FIGURE 7. A contact 2 of a third pair of contacts 2-3 is connected to ground at G-S through a Conductor 46. This contact 2 is also one of a rst pair of contacts 1-2. In the normal position of the relay the contact 2 is closed on the contact 1; in the operated position of the relay the contact 2 is closed on the contact 3. The contact 1 is connected by a conductor 47 to the tone generator and the latter is connected by a conductor 28 to the tone coloring circuit, as in the previous modications.

In other words, when relays Ry-Z and Ry-3 of FIG- URE 6 are not operated movable contact 2 remains closed on contact 1 grounding the output of the tone generators. When the relays are actuated during playing of the guitar, the grounds G-S are kremoved from the tone generators rby movable contact 2 contacting open contact 3, allowing the tonesof the tone generators to pass over conductors 28-28 to the coloring circuit, as generally shown in the embodiment of FIGURE 5.

In operation, as has already been pointed out, when the string 11 is depressed and contacts two fret segments 13-13, the contacts 4-5 of the relay in the adjacent stage operate to mute the next lower note, as do the contacts 9-10 in the previous modication. Operation of the relays Ry-l, Ry-2, Ry-3, etc. will open the contact 2 from the contact 1 and close same on the contact 3. This completes the circuit from the tone generator over conductors 47 and 28, through the tone coloring circuit, to ground, and return from ground at G-S over conductor 46 to the contact 3.

From the foregoing it will now be seen that there is herein provided an improved electronic guitar which accomplishes all of the objects of this invention and others including many advantages of great practical utility.

As many embodiments may be made of this inventive concept, and as many modifications may he made in the embodiments hereinbefore shown and described, it is to be understood that all matter herein is to be interpreted as merely illustrative and not in a limiting sense.

Having now fully described my invention, what I claim as new and useful and desire to secure by Letters Patent of the United States is:

1. A circuit for playing an organ from a guitar having circuit making and breaking means comprised by the 6 strings and frets n the linger board, including stages, tone generators connected to the respective stages, connections between the making and breaking means cooperating with said stages, a rst circuit, a tone coloring output circuit connected to said rst circuit and electrical connections between the successive stages of the iirst circuit for muting one note when the string on the guitar contacts successive frets.

2. A circuit for playing an organ from a guitar having circuit making and breaking means comprised by the strings and frets on the finger board, including stages, tone generators connected to the respective stages, a rst circuit, a tone coloring output circuit connected to the rst circuit, inputs from the tone generators, keying connections to the respective stages including connections between the circuit making and breaking means on the guitar, and octave selector switches cooperatively coupled with said inputs and said tone coloring output circuit.

3. A circuit for playing an organ from a guitar having circuit making and breaking means comprised by the strings and frets on the fingerboard, including stages, tone generators connected to the respective stages, a rst circuit, a tone coloring output circuit connected to the rst circuit, inputs from the tone generators, keying connections to the respective stages including connections between the circuit making and break-ing means on the guitar, three position octave selector switches connected in inputs from said keying connections, and a mechanical link interconnecting the octave selector switches for conjoint operation.

4. A circuit for playing an organ from a guitar having circuit making and breaking means comprised by the strings and frets on the nger board, including stages, each stage having an electron tube therein, a tone generator for each stage, a pair of blocking capacitors connected in series to the output of the respective tone generator and the grid of the electron tube, a muting circuit connection from the circuit making and breaking means on the guitar for one stage to the blocking capacitors for the next stage intermediate same, and a tone coloring output circuit connected to the anodes of the electron tubes of the several stages.

5. A circuit for playing an organ from a guitar having circuit making and breaking means comprised by the strings and frets on the linger board, including stages, each stage having an electron tube therein, tone generators including outputs for the respective stages connected to the grids of the electron tubes, a source of electro-motive force, a pair of balancing resistors connected in series between the grid of the electron tube and the source of electro-motive force in each stage, a keying circuit con-v nection from the circuit making and breaking means for the respective stage on the guitar to the balancing resistors connected intermediate the latter, and a tone coloring circuit connected to the anodes of the electron tubes in the various stages.

6. A circuit for playing an organ from a guitar having circuit making and breaking means comprised by the strings and frets on the nger board, including stages, each stage having an electron tube therein, tone generators for the respective stages connected to the grids of the electron tubes, a time delay circuit comprised by a series resistor connected to the grid of the electron tube for each stage and a parallel capacitor connected to ground, a keying connection from the circuit making and breaking means on the guitar for the respective stage to the series resistor,

and a tone coloring circuit connected to the anodes of the vacuum tubes in the various stages.

7. A circuit for playing an organ from a guitar having circuit making and breaking means comprised .by the strings and frets on the linger board, including stages, a relay in each stage having a plurality of sets of contracts, an energizing circuit for each relay including the circuit making and breaking contact means on the guitar for the respective stages and a pair of normally closed contacts on the relay in the next adja-cent stage, tone generators for each stage,a tone coloring circuit, and circuit connections from the tone generator in each stage through pairs of normally open contacts for connecting the tone, generator to the tone coloringzcircuit when the relay is energized.

8. A circuit for playing an organ from a guitar having circuit making and 'breaking means comprised by the strings and frets on the finger board, including stages, a relay in each stage having a plurality of sets of contacts, an energizing circuit for each relay including the circuit making and breaking means on the guitar for the respective stages, tone generators comprising gating means for each stage, a tone coloring circuit, and circuit connections from .the Itone generators to the tone coloring circuit including normally closed pairs of contacts of the relay and a ground connection and normally open pairs of contacts Vof the relay, which are closed when the relay is energized.

9. A circuit for playing an organ from a guitar having circuit making and breaking means comprised by thestrings and frets on the finger board, including stages, a relay in each stage having a plurality of sets of contacts, an energizing circuit for each relay including the circuit making and breaking means on the guitar for the respective stage, ,tone generators for each stage, a tone coloring circuit, circuit connections from the tone generators to the tone coloring circuit including normally closed pairs of contacts of the relay and a ground connection and normally open pairs of contacts, which are closed when the relay is energized, and a circuit to the tone generator in each stage including a source of electro-motive force, a switch, and a pair of normally open contacts of said relay. 10. A circuit for playing an organ from a guitar having circuit making and breaking means comprised by the strings and frets on the finger board, including stages, a relay in each stage for each fret having a plurality of pairs of contacts, a power supply for each relay, an energizing circuit for the relays along one string including the power supply, a circuit making and breaking means on the guitar for the respective stages, and a pair of normally closed contacts of the relay in the next adjacent stage, a tone generator for each stage, a tone coloring circuit, and circuit connections between the tone generators and the tone coloring circuit including pairs of contacts of said relays. l 11. A circuit for playing an organ from a guitar having circuit making and breaking means comprised ,by the strings and frets on the finger board, including stages, a relay in each stage for each fret having a plurality of pairs of contacts, a power supply for each relay, an energizing circuit for the relays along one string including the power supply and a circuit making and breaking means on the guitar for the respective stage, a tone `generator for each stage, a tone coloring circuit and circuit connections between the tone generator in each stage and the tone coloring circuit including a pair of normally closed contacts of said relay and a pair of normally open contacts of said relay, which latter are closed when the relay is energized.

12. A circuit for playing an `organ from a guitar hav ing circuit making and breaking means comprised by the strings and frets on the linger board, including stages, a relay in each stage for each fret having a plurality of pairs of contacts, a power supply for each relay, an energizing circuit for the relays along one string including the power supply and a circuit making and breaking means on the guitar for the respective stage, a tone generator for each stage, a tone coloring circuit, and circuit connections between the tone generator in each stage and the tone coloring circuit, including a pair of normally closed contacts of the relay and a ground connection, which contacts .are open when the relay is energized, and a pair of normally open contacts of the relay, which latter contacts are closed when the relay is energized.

13. A circuit for playing an organ from a guitar having a circuit making and breaking means for tones of the tone generators comprising a finger board having strings and frets thereon, including stages, tone generators having outputs connected to the respective stages, connections 'between the making and breaking means cooperating with said stages, a first circuit, a tone coloringroutput circuit adapted to be connected to selective gating means for connecting the outputs of said tone generator to said tone coloring output circuit, and electrical connections between the successive stages of the first circuit for muting a successive note when a string on the guitar contacts frets on said fingerboard.

References Cited by the Examiner UNITED STATES PATENTS 2,070,344 2/ 37 Waters S11-1.27 2,142,580 1/39 Williams 84-1.19 2,458,178 1/49 Langer 84-1.17 2,468,062 4/49 Hanert S4-1.11 X 2,562,670 7/51 Koehl 84.01 X

'5/57 Donahue ---a 84-1.l6 

1. A CIRCUIT FOR PLAYING AN ORGAN FROM A GUITAR HAVING CIRCUIT MAKING A BREAKING MEANS COMPRISED BY THE STRINGS AND FRETS ON THE FINGER BOARD INCLUDING STAGES, TONE GENERATORS CONNECTED TO THE RESPECTIVE STAGES, CONNECTIONS BETWEEN THE MAKING AND BREAKING MEANS COOPERATING WITH SAID STAGES, A FIRST CIRCUIT, A TONE COLORING OUTPUT CIRCUIT CONNECTED TO SAID FIRST CIRCUIT AND ELECTRICAL CONNECTIONS BETWEEN THE SUCCESSIVE STAGES OF THE FIRST CIRCUIT FOR MUTING ONE NOTE WHEN THE STRING ON THE GUITAR CONTACTS SUCCESSIVE FRETS. 